Symbiotic nitrogen fixers - nutrient cycles, Biology

Assignment Help:

Symbiotic Nitrogen Fixers - Nutrient Cycles

Of the symbiotic nitrogen fixing bacteria, species of Rhizobium form root nodules in legumes and are the most studied nitrogen fixers and the best understood. Species of Rhizobium are most specific to particular species of legumes. The rhizobia penetrate the root hair and once inside the root, the bacteria rapidly multiply and form swollen, irregular - shaped bodies in roots of legumes. Some non-legume w6ody plants also have root nodules and fix nitrogen symbiotically.

The organisms that cause the formation of nodule and fixation of nitrogen are actinomycetes (a kind of primitive fungus). Some examples of non-legumes are species of Alnus, Elaeagnus Myrica, Araucaria, Ginkgo, and Casuarina. Unlike legumes, which are largely tropical in origin, these nitrogen fixers originate in the temperate zone. Nitrogen fixation by blue green algae or cyanobacteria may take place in free living forms or in symbiosis with fungi as in certain lichens, mosses ferns and at least one seed plant. The fronds of the small free floating aquatic fern Azolla contain small pores filled with symbiotic blue green algae Anabaena that actively fix nitrogen. For centuries this fern has played an important role in the rice fields of China. Before the rice fields are planted the water filled paddy fields are covered with the aquatic fern which fixes enough nitrogen for the crop as it matures. This practice permits rice to be grown without further addition of nitrogen fertilisers. Symbiotic nitrogen fixers are more efficient than free living ones.


Related Discussions:- Symbiotic nitrogen fixers - nutrient cycles

Define sympathetic and the parasympathetic neural actions, Q. What is the a...

Q. What is the antagonism between the sympathetic and the parasympathetic neural actions? In general the action of the parasympathetic and the sympathetic are antagonistic that

What is biodiversity, Q. What is biodiversity? The Biological diversity...

Q. What is biodiversity? The Biological diversity is the variety of species of living beings of an ecosystem. In the ecosystems which are more biodiverse, like tropical forests

What are the five human digestive secretions, Q. What are the five human di...

Q. What are the five human digestive secretions? Which of them is the only pne that does not contain digestive enzymes? The human digestive secretions are: bile, saliva, gastri

Benefits of haccp, The benefits of HACCP  can be  summarized  as under. ...

The benefits of HACCP  can be  summarized  as under. a)  Benefits to Consumers Reduced risk of food borne diseases Increased confidence in food supply Increased awar

What about whale fins compared to fish fins, Q. Are the limbs modified into...

Q. Are the limbs modified into wings of bats and the wings of birds instance of evolutionary homology or analogy? What about whale fins compared to fish fins? Bird and Bat wing

Ribosomes in eukaryotic, Q. How dissimilar are the location of ribosomes in...

Q. How dissimilar are the location of ribosomes in eukaryotic and in prokaryotic cells? In eukaryotic cells they can also be found free in cytoplasm and mainly adhered to the e

Cardiac transplantation, For patients with end-stage heart failure, cardiac...

For patients with end-stage heart failure, cardiac transplantation has become a promising therapy especially with the advent of  immunosuppressive therapy and more careful screenin

Explain oxidation-reduction potential, Oxidation-reduction  Potential (ORP)...

Oxidation-reduction  Potential (ORP) ORP is related to the concentration of oxidizers or reducers in a solution, and their activity or strength. It provides an indication of th

Adaptations, what are some adaptations of flatworms

what are some adaptations of flatworms

Hybridization, Hybridization  is the reaction by which pairing of the compl...

Hybridization  is the reaction by which pairing of the complementary strands of nucleic acid happens. DNA is usually double-stranded, and when these strands are separated form each

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd